St. Alphonsus was founded in 1840. Catholic settlement in the area began as early as 1790. The early settlers were farmers, both Irish and Germans. To attend Mass, these Catholics had to either depend on the occasional visit from a missionary priest, or, after 1808, to travel to Pittsburgh to visit St. Patrick. The first known Mass in the area was celebrated in a private home in 1832. In 1835, the Bishop of Philadelphia visited Wexford. While there a local Catholic gave him a deed for land for a church.
The actual building of a church did not occur until after the Redemptorist Fathers arrived in Pittsburgh and founded St. Philomena and took responsibility for the Catholics in Wexford. The cornerstone for the new church was laid in May 1840 and the completed church was dedicated on July 19, 1840.
For the first 24 years, St. Alphonsus was a mission of other parishes. At various times it was a mission of St. Philomena, St. Mary in Sharpsburg, Ss. Peter and Paul in Beaver and St. Peter in Allegheny City (now Pittsburgh's North Side). Sometime between 1843 and 1860, the original church was destroyed in a storm and a new church was built.
In 1864, the parish received its first resident pastor. As the population grew over the years, the need for a larger church became obvious. A new church was built in 1889. As the population continued to grow, the church again became too small. Rather than build a new church, the parish renovated and expanded the existing church in 1912. The seating area was extended and two sacristies, a new sanctuary and altars, confessionals and a baptismal font were added.
In the 1960's, the congregation again outgrew the existing church. Again the parish decided to expand the existing church rather than build a new building. This expansion took place in 1968. The original church building was renovated in 1976.
With the turn of the century, trends in the Diocese of Pittsburgh began to reveal a decline in Mass attendance and sacramental participation. At the same time, the number of priests available for parish ministry also began to decline.
To address these challenges, Bishop David Zubik announced on April 12, 2015 a new diocesan initiative, On Mission for The Church Alive!, a consultative strategic planning process designed to foster viable, sustainable and vibrant parishes. As part of this process, the Bishop, in consultation with the faithful, began to consider new models of parish life based on pastoral needs, financial and temporal resources and available clergy.
In 2018, following the period of consultation, parishes were grouped together and served by a single clergy team to eventually form one new parish.
During this transition period, St. Alphonsus Parish remained an independent parish while sharing clergy and staff and eventually publishing a joint bulletin with the other parish. This ended on July 1, 2020 when St. Alphonsus Parish merged with the other parish in Wexford, St. Alexis to form the new St. Aiden Parish. As part of the merger St. Alphonsus Church remained open as part of the new parish.